Fix clang-tidy warnings in aapt and aapt2.

* Add explicit keyword to conversion constructors.
* Add NOLINT(implicit) comments for implicit conversion constructors.
Bug: 28341362
* Use const reference type for read-only parameters.
Bug: 30407689
* Add NOLINT to suppress wrong clang-tidy warnings on macros.
Test: build with WITH_TIDY=1

Change-Id: Ibfafb23d9be463b4072745a51a6d9f1812dcac45